Wireless Power Transfer for Elevator Car Subsystems
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Solution Overview
Problem
Electromechanical propulsion systems face challenges in providing on-board power to moving structures without tethers, particularly in self-propelled elevator systems, where existing systems rely on moving cables or current collectors, which are cumbersome and inefficient.
Innovation Solution
The implementation of a wireless power transfer system using a secondary winding that utilizes the excitation switching frequency ripple to generate current for powering elevator car subsystems, with primary windings and a converter outputting excitation currents that include base and ripple frequency components, allowing for efficient wireless power transfer and propulsion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If moving cables or current collectors are used to provide power to the elevator car, then power can be supplied to the moving structure, but the system becomes cumbersome and inefficient
Solution Approach 1:
The patent replaces the mechanical power transmission system (moving cables or current collectors) with an electromagnetic field-based wireless power transfer system. The stationary primary windings generate a time-varying magnetic field that induces current in the moving secondary winding on the elevator car, eliminating the need for mechanical electrical connections and thereby reducing system complexity while improving power supply efficiency.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary to transfer power from the stationary primary windings to the moving secondary winding. This magnetic field mediator enables wireless energy transfer without direct mechanical or electrical contact, resolving the contradiction between providing power to moving structures and avoiding cumbersome mechanical connections.
2Use of energy by moving object
If wireless power transfer is implemented using secondary winding and excitation switching frequency ripple, then power transfer efficiency improves and weight is reduced, but system reliability must be maintained
Solution Approach 1:
The patent makes the primary windings serve dual functions: generating propulsion force through base frequency excitation and enabling wireless power transfer through switching frequency ripple. This multi-functionality improves power transfer efficiency without adding separate dedicated power transmission components, thereby reducing weight while maintaining system reliability through the robustness of the electromechanical propulsion system itself.
3Weight of moving object
If mechanical connections are eliminated for power transfer, then weight is reduced and system reliability is enhanced, but the complexity of wireless power transfer must be managed
Solution Approach 1:
The patent extracts and eliminates the heavy mechanical power transmission components (cables, collectors, contacts) from the elevator car system. By removing these unnecessary mechanical elements and relying on the electromagnetic field for power transfer, the moving weight is significantly reduced while the wireless power transfer complexity is minimized by utilizing the existing propulsion electromagnetic field.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables reliable, efficient, and weight-reduced power transfer to elevator car subsystems, eliminating the need for mechanical connections and enhancing system reliability and safety by leveraging existing excitation arrangements and reducing component size.
Implementation Method 1
a secondary winding coupled to the elevator car and disposed adjacent to the permanent magnet along the direction of travel, and wherein the secondary winding is configured to utilize an excitation switching frequency ripple to generate a current to power the car subsystem
Implementation Method 2
a plurality of primary windings positioned along the hoistway; a permanent magnet coupled to the elevator car, the plurality of primary windings and the permanent magnet defining an electromechanical propulsion system for imparting motion to the elevator car
Data Source
AI summary
An elevator system includes an elevator car having an electrically powered car subsystem. A guide rail of the elevator system is constructed and arranged to guide the elevator car along a hoistway and in a direction of travel. An electromechanical propulsion system includes plurality of primary windings positioned along the hoistway, and a permanent magnet coupled to the elevator car for imparting motion to the elevator car in response to a drive excitation. A secondary winding is coupled to the elevator car and disposed adjacent to the permanent magnet along the direction of travel, and wherein the secondary winding is configured to utilize an excitation switching frequency ripple to generate a current to power the car subsystem.